Abstract

Suppressor of cytokine signaling (SOCS) proteins arerecognized as key feedback inhibitors modulating theinflammatory activities of macrophages, but comparativelylittle is known about whether and how they affectphagocytosis. Here, we evaluated the role of SOCS3 indriving the inflammatory phenotype and phagocyticuptake of apoptotic cells by human macrophages andthe signaling pathways that are necessary for efficientphagocytosis. In M1-activated human monocyte-derivedmacrophages, SOCS3 silencing, using short interferingRNA technology, resulted in a decreased expression ofproinflammatory markers and an increased expressionof M2 macrophage markers. Strikingly, we demonstratedfor the first time that SOCS3 knockdownsignificantly enhances the phagocytic capacity of M1macrophages for carboxylate-modified beads andapoptotic neutrophils. With the use of live-cell videomicroscopy, we showed that SOCS3 knockdown radicallyaffects the temporal dynamics of particle engulfment,enabling more rapid uptake of a secondtarget and delaying postengulfment processing, asevidenced by deferred acquisition of phagosomematuration markers. SOCS3 knockdown impacts onphagocytosis through increased PI3K and Ras-relatedC3 botulinum toxin substrate 1 (Rac1) activity, pathwaysessential for engulfment and clearance of apoptoticcells. Enhanced phagocytosis in SOCS3-silenced cells was reversed by pharmacological PI3Kinhibition. Furthermore, we revealed that actin polymerization,downstream of PI3K/Rac1 activation, wassignificantly altered in SOCS3-silenced cells, providinga mechanism for their greater phagocytic activity. Thefindings support a new model, whereby SOCS3 notonly plays an important role in driving macrophageinflammatory responses but modulates key signaling pathways organizing the actin cytoskeleton to regulatethe efficiency of phagocytic processes. J. Leukoc. Biol.100: 000–000; 2016.

abstract = "Suppressor of cytokine signaling (SOCS) proteins arerecognized as key feedback inhibitors modulating theinflammatory activities of macrophages, but comparativelylittle is known about whether and how they affectphagocytosis. Here, we evaluated the role of SOCS3 indriving the inflammatory phenotype and phagocyticuptake of apoptotic cells by human macrophages andthe signaling pathways that are necessary for efficientphagocytosis. In M1-activated human monocyte-derivedmacrophages, SOCS3 silencing, using short interferingRNA technology, resulted in a decreased expression ofproinflammatory markers and an increased expressionof M2 macrophage markers. Strikingly, we demonstratedfor the first time that SOCS3 knockdownsignificantly enhances the phagocytic capacity of M1macrophages for carboxylate-modified beads andapoptotic neutrophils. With the use of live-cell videomicroscopy, we showed that SOCS3 knockdown radicallyaffects the temporal dynamics of particle engulfment,enabling more rapid uptake of a secondtarget and delaying postengulfment processing, asevidenced by deferred acquisition of phagosomematuration markers. SOCS3 knockdown impacts onphagocytosis through increased PI3K and Ras-relatedC3 botulinum toxin substrate 1 (Rac1) activity, pathwaysessential for engulfment and clearance of apoptoticcells. Enhanced phagocytosis in SOCS3-silenced cells was reversed by pharmacological PI3Kinhibition. Furthermore, we revealed that actin polymerization,downstream of PI3K/Rac1 activation, wassignificantly altered in SOCS3-silenced cells, providinga mechanism for their greater phagocytic activity. Thefindings support a new model, whereby SOCS3 notonly plays an important role in driving macrophageinflammatory responses but modulates key signaling pathways organizing the actin cytoskeleton to regulatethe efficiency of phagocytic processes. J. Leukoc. Biol.100: 000–000; 2016.",

note = "ACKNOWLEDGMENTS This work was supported by Kidney Research UK (Grant Number RP1/2012). The authors thank the staff of the Aberdeen Microscopy and Histology Core Facility for advice and technical assistance. The authors acknowledge and are grateful to all volunteers for donating blood for macrophage and neutrophil isolation.",

year = "2016",

month = oct,

doi = "10.1189/jlb.3A1215-554RR",

language = "English",

volume = "100",

pages = "771--780",

journal = "Journal of Leukocyte Biology",

issn = "0741-5400",

publisher = "FASEB",

number = "4",

}

TY - JOUR

T1 - SOCS3 is a modulator of human macrophage phagocytosis

AU - Gordon, Peter

AU - Okai, Blessing

AU - Hoare, Joseph I

AU - Erwig, Lars P

AU - Wilson, Heather M

N1 - ACKNOWLEDGMENTS
This work was supported by Kidney Research UK (Grant Number
RP1/2012). The authors thank the staff of the Aberdeen
Microscopy and Histology Core Facility for advice and technical
assistance. The authors acknowledge and are grateful to all volunteers
for donating blood for macrophage and neutrophil isolation.

PY - 2016/10

Y1 - 2016/10

N2 - Suppressor of cytokine signaling (SOCS) proteins arerecognized as key feedback inhibitors modulating theinflammatory activities of macrophages, but comparativelylittle is known about whether and how they affectphagocytosis. Here, we evaluated the role of SOCS3 indriving the inflammatory phenotype and phagocyticuptake of apoptotic cells by human macrophages andthe signaling pathways that are necessary for efficientphagocytosis. In M1-activated human monocyte-derivedmacrophages, SOCS3 silencing, using short interferingRNA technology, resulted in a decreased expression ofproinflammatory markers and an increased expressionof M2 macrophage markers. Strikingly, we demonstratedfor the first time that SOCS3 knockdownsignificantly enhances the phagocytic capacity of M1macrophages for carboxylate-modified beads andapoptotic neutrophils. With the use of live-cell videomicroscopy, we showed that SOCS3 knockdown radicallyaffects the temporal dynamics of particle engulfment,enabling more rapid uptake of a secondtarget and delaying postengulfment processing, asevidenced by deferred acquisition of phagosomematuration markers. SOCS3 knockdown impacts onphagocytosis through increased PI3K and Ras-relatedC3 botulinum toxin substrate 1 (Rac1) activity, pathwaysessential for engulfment and clearance of apoptoticcells. Enhanced phagocytosis in SOCS3-silenced cells was reversed by pharmacological PI3Kinhibition. Furthermore, we revealed that actin polymerization,downstream of PI3K/Rac1 activation, wassignificantly altered in SOCS3-silenced cells, providinga mechanism for their greater phagocytic activity. Thefindings support a new model, whereby SOCS3 notonly plays an important role in driving macrophageinflammatory responses but modulates key signaling pathways organizing the actin cytoskeleton to regulatethe efficiency of phagocytic processes. J. Leukoc. Biol.100: 000–000; 2016.

AB - Suppressor of cytokine signaling (SOCS) proteins arerecognized as key feedback inhibitors modulating theinflammatory activities of macrophages, but comparativelylittle is known about whether and how they affectphagocytosis. Here, we evaluated the role of SOCS3 indriving the inflammatory phenotype and phagocyticuptake of apoptotic cells by human macrophages andthe signaling pathways that are necessary for efficientphagocytosis. In M1-activated human monocyte-derivedmacrophages, SOCS3 silencing, using short interferingRNA technology, resulted in a decreased expression ofproinflammatory markers and an increased expressionof M2 macrophage markers. Strikingly, we demonstratedfor the first time that SOCS3 knockdownsignificantly enhances the phagocytic capacity of M1macrophages for carboxylate-modified beads andapoptotic neutrophils. With the use of live-cell videomicroscopy, we showed that SOCS3 knockdown radicallyaffects the temporal dynamics of particle engulfment,enabling more rapid uptake of a secondtarget and delaying postengulfment processing, asevidenced by deferred acquisition of phagosomematuration markers. SOCS3 knockdown impacts onphagocytosis through increased PI3K and Ras-relatedC3 botulinum toxin substrate 1 (Rac1) activity, pathwaysessential for engulfment and clearance of apoptoticcells. Enhanced phagocytosis in SOCS3-silenced cells was reversed by pharmacological PI3Kinhibition. Furthermore, we revealed that actin polymerization,downstream of PI3K/Rac1 activation, wassignificantly altered in SOCS3-silenced cells, providinga mechanism for their greater phagocytic activity. Thefindings support a new model, whereby SOCS3 notonly plays an important role in driving macrophageinflammatory responses but modulates key signaling pathways organizing the actin cytoskeleton to regulatethe efficiency of phagocytic processes. J. Leukoc. Biol.100: 000–000; 2016.

KW - live-cell imaging

KW - PI3K

KW - Rac1

U2 - 10.1189/jlb.3A1215-554RR

DO - 10.1189/jlb.3A1215-554RR

M3 - Article

VL - 100

SP - 771

EP - 780

JO - Journal of Leukocyte Biology

JF - Journal of Leukocyte Biology

SN - 0741-5400

IS - 4

ER -

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